III-V semiconductor materials, such as, for example, III-arsenides (e.g., Indium Gallium Arsenide (InGaAs)), III-phosphides (e.g., Indium Gallium Phosphide (InGaP)) and III-Nitrides (e.g., Indium Gallium Nitride (InGaN)), may be employed in a number of electronic device structures. Some example electronic devices are switching structures (e.g., transistors, etc.), light emitting structures (e.g., laser diodes, light emitting diodes, etc.), light receiving structures (e.g., waveguides, splitters, mixers, photodiodes, solar cells, solar subcells etc.), and/or microelectromechanical system structures (e.g., accelerometers, pressure sensors, etc). Such electronic device structures containing III-V semiconductor materials may be used in a wide variety of applications. For example, such device structures are often used to produce radiation (e.g., visible light) at one or more of various wavelengths. The light emitted by such structures may be utilized not only for illumination applications, but may also be used in, for example, media storage and retrieval applications, communications applications, printing applications, spectroscopy applications, biological agent detection applications, and image projection applications.
In greater detail, the InGaN layer may initially grow “pseudomorphically” to the underlying substrate, such that a lattice parameter of the InGaN layer is caused (e.g., forced by atomic forces) to substantially match a lattice parameter of the underlying substrate upon which it is grown. The lattice mismatch between the InGaN layer and the underling substrate (e.g., GaN) may induce strain in the crystal lattice of the InGaN layer, and this induced strain may induce a strain energy which may increase with increasing thickness of the InGaN layer. As the thickness of the InGaN layer increases with continued growth thereof, the strain energy in the InGaN layer may increase until, at a thickness commonly referred to as the “critical thickness,” the InGaN layer may no longer grow in a pseudomorphic manner and may undergo strain relaxation. Strain relaxation in the InGaN layer may result in a deterioration of quality of the InGaN layer. For example, such deterioration in crystal quality in the InGaN layer may include the formation of crystalline defects (e.g., dislocations), a roughening of an InGaN layer surface, and/or the formation of regions of inhomogeneous material composition.
In some cases, these defects may cause the device to be ineffective. For example, defects may be significant enough to cause a short across a P-N junction of light emitting diodes (LEDs) or laser diodes, such that the light emitting device cannot generate the desired electromagnetic energy.
There is a need for III-V semiconductor structures and methods for forming such III-V semiconductor structures that have reduced defect densities to increase the quality of devices formed therewith. In particular, there is a need for III-V semiconductor structures and method for forming them that include Indium alloyed with other materials to form an Indium containing layer with reduced defects densities that is relatively thick, has relatively high Indium concentrations, or combination thereof.